ECON 1540 Quiz: test1verREDanswers.pdf

• School: York University
• Department: Economics
• Course: ECON 1540
• Professor: Vassilios Bardis

Document Summary

Suppose matrix a is 4x5, matrix b is 8x4, matrix c is 5x5 and matrix c is symmetric. A is 4x5 => a" is 5x4 and a"a is 5x5. If so, what is its dimension? (5 marks) A" is 5x4 and b" is 4x8 => a"b" is 5x8 => (a"b")" is 8x5. It follows that (a"b")"a" is 8x4. (c) determine the dimension of matrix p = a"(b"b)a and whether it is symmetric. (5 marks) If p" = p, then p is symmetric (1 mark) P" = (a"(b"b)a)" = a" (a"(b"b))" = a" (b"b)" (a")" = a" b" (b")" a = a" (b"b) a = p (d) determine the dimension of matrix z = c(b"b)a and whether it is symmetric. (5 marks) C is 5x5 but b" is 4x8, i. e. number of columns of c is different from the number of columns of b"b.